In such an electrophotographic image forming apparatus which employs, for example, a photosensitive drum as an image carrying member, it is known to perform the following basic electrophotographic process in which reverse development method is employed:
Firstly, the surface of a photosensitive drum is uniformly charged by a charger in a dark place. For exposure, light is then directed from an exposure device to an image portion formed on the surface of the photosensitive drum thus uniformly charged and the electrical charge on the illuminated image portion is eliminated to decrease the electric potential, thereby forming an electrostatic latent image of a square well potential. Thereafter, toner, which is charged to the same polarity as that of the uniform charge applied on the surface of the photosensitive drum, is adhered to the electrostatic latent image by a developing device, utilizing an electric field formed by a developing bias, in order to form a visible toner image. Sequentially, a transfer sheet is overlaid on the toner image and electrical charge opposite in polarity to the charge of the toner is applied to the transfer sheet by a transfer device so that the toner image is transferred onto the transfer sheet owing to electrostatic force. The transfer sheet is further discharged by a discharging separator to reduce the electrostatic attraction force effecting on the photosensitive drum so that the transfer sheet is separated from the photosensitive drum. Thereafter, heat or pressure is applied by the fixing device to the toner image which has been transferred onto the transfer sheet so as to be fused to form a permanent image.
The transfer device is disposed in an opposed position to the photosensitive drum with a delivery path for the delivery of the transfer sheet interposed therebetween. A discharging separator is, likewise, disposed opposite to the photosensitive drum with the delivery path interposed therebetween and located adjacent to the transfer device downstream in the sheet delivery direction of the delivery path. In the upstream of the transfer device and the discharging separator in the sheet delivery direction of the delivery path, a pair of stand-by rollers are arranged in opposing relationship. The stand-by rollers allow the leading edge of the transfer sheet, which has been sent out of a cassette or tray by any of known separation means, to be in register with the leading edge of a toner image electrostatically held by the photosensitive drum. The stand-by rollers also function to send the transfer sheet to the transfer device and then to the discharging separator, adjusting it so as not to deflect diagonally from the sheet delivery direction. In the downstream of the stand-by rollers in the sheet delivery direction of the delivery path, a fixing device comprising a fixing roller and a pressure roller which are arranged in opposing relationship is disposed such that the distance between the stand-by rollers and the fixing device is not more than the length of the transfer sheet running in parallel with its delivery direction and such that the transfer device and the discharging separator are positioned between the stand-by rollers and the fixing device.
In the conventional image forming apparatus, or more particularly, in a discharging separator of the above type, the transfer sheet is discharged by the discharging separator, such that the entire part of the transfer sheet can be evenly separated from the photosensitive drum.